Boeing said it has discovered a manufacturing issue with some 737 Max aircraft, although it insisted the problem is not “an immediate safety of flight issue.” A supplier used a “non-standard manufacturing process” during the installation of two fittings in the rear fuselage, Boeing said in a statement to CNN. The company said Max jets can continue flying while inspections are underway and the Federal Aviation Administration said it “validated” that conclusion. It already subjects new 737 Max aircraft to greater scrutiny than it does other newly manufactured planes prior to delivery following two fatal 737 Max crashes. Boeing declined to say how many 737 Max planes are affected, beyond calling it a “significant number.” Shares are down nearly 6% in premarket trading. United Airlines said it doesn’t expect “any significant impact on our capacity plans for this summer or the rest of the year.” Southwest Airlines\n \n (LUV) said it would work with Boeing on “any needed inspections or part replacements.” Boeing\n \n (BA) has reported only two profitable quarters in the nearly four years since the grounding of the 737 Max. After two fatal crashes that killed 346 people, the jet was grounded for 20 months starting in March 2019. Then a year later, the pandemic brought demand for flying and new aircraft to a near halt — sparking the cancellation of hundreds of jet orders and the pileup of losses for Boeing\n \n (BA). Boeing’s problems in the fourth quarter are tied to its difficult few years since the 737 Max crisis. For one, the company was saddled with excess inventory of hundreds of the jets. Usually Boeing doesn’t hold onto inventory, as planes are delivered to customers soon after completion. But even though the 737 Max jets couldn’t be delivered during the grounding, Boeing kept building them — partly to keep its suppliers in business. Then it was forced to find new buyers for some of those planes due to customers canceling orders during the pandemic.